I type these words with cranberry[7] stickiness under my fingernails and the faint but unmistakable scent of turkey lingering about my person (I don’t think Buddha, my white lab, has stopped following me around all weekend, sneaking in the odd lick to an elbow still glistening with turkey grease; and, yep, he just got me again). The massive poultry carcass just finished three days of simmering for stock, odd bits of breast meat and yam and solidified gravy popping up on every shelf in the fridge, empty wine bottles holding an Occupy Kitchen Counter. Ah, Thanksgiving, how I love you.

A staple of Thanksgiving seems to be fretting over holiday treats, only it’s a little different in the Primal community. Instead of freaking out over the saturated fat[8] content of a dollop of whipped cream on a slice of pumpkin pie, we agonize over the gluten[9] content, wonder if baking truly deactivated all the wheat germ agglutinin present in the crust, and speculate about how our gut flora[10] will react to the fiber in the pumpkin filling. And when we make our own versions of holiday baked goods, like almond meal[11] this or walnut flour[12] that, we worry about the potential oxidation of the heated omega-6 polyunsaturated fats[13] in the nuts. In fact, in the past week, I have received several questions on this very topic:

Dear Mark,

With all the delicious Primal recipes out there for holiday baked goodies, I have to wonder if they might actually be doing my health more harm than good. Does baking with nuts/nut butters turn them from a nutritious whole food and healthy snack into an oxidized omega-6 disaster?

Thanks!

Alyssa

There are several questions (and sub-questions) that need addressing here. First, do the omega-6 polyunsaturated fats in nuts oxidize when you heat them[14]? Second, if they do, does the degree of oxidation from heating increase when you use ground nuts? Third, even if nut fats oxidize to some degree after heating, does it matter if we eat them? When the rubber hits the road, when the partially oxidized nut lipids hit the GI tract, what happens? Does eating said nut products translate to increased inflammation in the body or more oxidation of serum lipids? Well, let’s look into it.

Unfortunately (and unsurprisingly), I was unable to find any studies that specifically examined Primal or paleo nut-based baked goods. I did find some interesting research on the stability of nuts when exposed to heat and some on the stability of blood lipids after eating nuts. It’s not what we’re looking for, not exactly, but from the available data we can divine some useful information and perhaps even make an educated guess or two about whether that Primal pie crust is okay or not.

So, heating nuts. There’s actually not a ton of data on the effect of roasting on nut lipids, but there’s some.

Dry roasting hazelnuts and almonds is gentler than “oil roasting,” which is really just deep frying in oil, and results in less oxidation of lipids (PDF[19]).

What’s cool about nuts is that they’re not just passive little balls of MUFA and PUFA[20], nice bite-sized vegetable oil snacks. You may not want nuts to oxidize[21] because you don’t want to eat the rancid fats, but nuts have some real skin in the game, too; if they oxidize prematurely, they don’t germinate and grow up to be trees. To avoid this, the lipids are located within individual cells, protected by dense networks of cell walls made of polysaccharides lined with phenolic compounds designed to prevent the oxidation of the admittedly fragile fats. Simply put, the stability of a nut exposed to heat depends on a few things – its polyunsaturated fat content (more PUFA[13] means more susceptibility, more MUFA[22] means more stability), its antioxidant content (flavonoids and other antioxidants like vitamin E protect against oxidation[23]), temperature, and the method of heating (dry roasting is gentler, oil roasting is harsher).

What about eating them?

Roasted almonds, raw almonds, and roasted almond butter all improved lipid numbers in one study[24], with the butter having the smallest impact. So, roasted pulverized almonds are less good, but still pretty good.

A big review of nuts and oxidation (PDF[25]) found that for the most part, eating nuts improves serum lipid stability. It either reduces markers of oxidative stress or increases the resistance of lipids[26] against oxidizing. And in the studies that showed no benefit, there were also no negatives. It was either beneficial or neutral. Almonds usually had better effects on oxidation than walnuts (lower PUFA, more MUFA). Of course, though most of the studies used raw nuts, the ones that used heated nuts still found benefits. Not too much data on heated ground-up nuts, sadly. There was a study that used almond meal muffins (although they weren’t exclusively almond meal). Eating those had no effect on lipid oxidation, neither good nor bad.

In other words, if eating nuts doesn’t improve the situation, it at least doesn’t worsen it. Then again, we have to take these studies with a grain of salt and consider the subjects’ baseline diets. These were not Primal subjects on a strict Primal – but nut-free – eating plan who experienced benefits upon incorporating nuts into their diets. These studies are by and large conducted using representatives of the general population, the same general population that eats a bad diet, is overweight trending toward obese, ingests a litany of pharmaceuticals, and leads a sedentary, stressful life. Replace their Cheezits with almonds and you’ll absolutely see some miraculous health benefits. I don’t think anyone would disagree.

But what if you add nut-based muffins and pancakes to a Primal eater’s daily arsenal of grass-fed beef[27], coconut[28], liver[29], eggs[30], leafy greens[31], berries[32], and sweet potatoes[33]? Do good things happen? Bad things? Neutral things? Now, some of us in the Primal camp are overweight, eat less-than-ideally, have a few prescriptions, and don’t move[34] and avoid stress[35] as often as we’d like (and indeed a lot get involved with this stuff to avoid or defeat said maladies of the general population), but we are generally better off than the average eater. But what happens?

Definitive studies on Primal treats don’t exist, so I won’t be citing anything. But I’ve gathered plenty of feedback from readers, and I think I’ve got a pretty good idea of how these Primal treats affect us. As treats, as special occasions, they appear to be fine. And remember: even if those people in the nut studies who saw the most benefit from eating almonds or walnuts were strict SAD-eaters, that just indicates that the occasional Primal nut-based baked indulgence is a better cheat choice than pizza, pie, and fries.

As staples, as regular parts of the daily diet, they may cause problems.

It should go without saying that you shouldn’t eat Primal almond meal pancakes[36] that use a cup of pure almond meal every morning for breakfast, because, well, a cup of tightly packed pure almond mass is over 1000 calories with more than 13 grams of omega-6 PUFAs. And that’s not including the eggs and coconut milk you used to bind it, the grass-fed butter you slathered on it, nor the blueberry reduction you drizzled all over it. Almonds, eggs, coconut, butter, blueberries (with, let’s face it, some sausage on the side) are all fantastic, delicious, nutritious Primal foods, but a lumberjack you ain’t (if you’re a lumberjack and you’re reading this, you have my apologies and my blessing to consume almond meal pancakes regularly). Most of you don’t need all that food every morning. There are limits. The studies that show benefits to nut consumption use reasonable amounts, usually around 50 or 60 grams, which is a large handful of nuts. 200 grams of almonds with the protective cell walls pulverized and subjected to heat? It might add up over time.

Exercise moderation with the baked goods. Be smart and pay attention to what they’re doing to your body. If you find yourself gaining weight after too many walnut meal pie crusts, maybe cancel your Amazon subscription to the nut flour variety pack. All in all? Don’t eat this stuff all the time. They’re treats. They’re not really health foods, regardless of the quality of ingredients used. Just like you wouldn’t eat cupcakes every day and think you were making a massive contribution to your health, don’t eat almond muffins every morning and call it breakfast. And remember, if you’re going to eat nuts, the best option in my book are macadamias[37], hands down.

[18] more resistant to oxidation: http://books.google.com/books?id=zJloknx0L6kC&pg=PA207&lpg=PA207&dq=roasted+walnuts+lipid+peroxidation&source=bl&ots=CAUHx3zWdd&sig=Xa1EonZXn6PaIX6j09we6QY8lYM&hl=en&ei=cqzTToT5NuOkiQLAodi8Cw&sa=X&oi=book_result&ct=result&resnum=3&ved=0CFIQ6AEwAg#v=onepage&q=roasted%20walnuts%20lipid%20peroxidation&f=false